This invention relates to monitoring.
The invention is more particularly concerned with arrangements for monitoring defects caused during the life of a mechanical component, such as a component in an aircraft.
Aircraft structural components and moving components can be subject to excessive stress, which can lead to damage in the components. It is known to attach stress monitors on such components. Although these can detect stress in the components they cannot detect defects arising from such stress. Defects within a component can be monitored by ground-based equipment during periodic inspection but this does not enable defects arising during use to be detected until the next inspection. In an aircraft, a defect caused during flight could lead to catastrophic failure unless action is taken to avoid this.
It is an object of the present invention to provide an improved monitoring system and method.
According to one aspect of the present invention there is provided a monitoring system including a component to be monitored, at least one phased acoustic array acoustically coupled with the component, and means for monitoring the output of the array during use of the component, the monitoring means being responsive to defects arising during use of the component and providing an output in accordance therewith.
The monitoring means preferably provides the output in response to a change in output from the acoustic array. The array is preferably energized to generate acoustic energy propagated into the component and may be energized to scan a beam of acoustic energy in two planes. The array may be provided by a square of PZT material diced into an array of square elements and is preferably operative at ultrasonic frequencies. The array may be bonded to the component and the system may include a plurality of arrays distributed over the component.
According to another aspect of the present invention, there is provided an aircraft including a component to be monitored, at least one acoustic array acoustically coupled with the component, and means in the aircraft for monitoring the output of the array during aircraft flight, the monitoring means being responsive to defects arising during flight and providing an output in accordance therewith.
The aircraft preferably includes a pilot display arranged to receive an output from the monitoring means. The monitoring means may be arranged to provide an output to an aircraft flight control system when the monitoring means detects a possible fault in the component, so as to limit the flight envelope of the aircraft.
According to a further aspect of the present invention there is provided a method of monitoring defects in a component during use of the component comprising the steps of acoustically coupling to the component at least one phased acoustic array, and monitoring the output of the array during use of the component so as to detect any defect arising during use of the component.
The method preferably includes the step of monitoring the output of the array for a change in output. The method preferably includes the step of energizing the acoustic array to produce a beam of acoustic energy that scans the component. The acoustic array is preferably energized to produce a beam of acoustic energy that scans the component in two planes.
An aircraft monitoring system and its method of use, in accordance with the present invention, will now be described, by way of example, with reference to the accompanying drawings.